||600-500 million years ago
||Algae, and invertebrae similar to jellyfish and worms. The firstshelled animals begin to appear in the Cambrian period. Arthopods, Brachiopods,Trilobytes
||500-440 million years ago
||Graptolites, Orthoceras, and primitive fish - the first verterbrates begin to appear.
||440-395 million years ago
||The first true plants appear. Crinoids are abundant, and eurypterids- believed to be the first air-breathing animal appears.
||395-345 million years ago
||Fish evolve into more complex animals, sharks and amphibians multiply.
||345-280 million years ago
||Ferns are plentiful and the first reptiles evolve from the amphibians.Spiders, cockroaches, scorpions appear. First animals to live on dry land.
||280-225 million years ago
||Reptiles become abundant. Trees similar to the pine develop, trilobytes become extinct.